In prior packet transmission systems and/or switching systems excessive performance degradation results because of congestion at packet nodes. The congestion is typically caused by an inability to route efficiently the packets being transmitted from one transmission or switching route to another when necessary. In other prior known packet systems, so-called alternate routing of packets is used in an attempt to mitigate the performance degradation.
One serious problem in such prior systems is that the alternate routing could cause certain types of packets to get out of sequence. This, of course, causes degraded performance, especially for packets transporting so-called periodic, e.g., voice type, information. Another problem with the prior systems including alternate routing is that when there is a relatively high level of overall congestion in the system, a so-called "funeral effect", i.e., deadlock, resulted. The "funeral effect" is a condition in which packet throughput in the system becomes increasingly less as the load on the system increases. This undesirable result is caused by packets being re-transmitted from their respective sources after the lapse of a predetermined interval without receiving an acknowledgment of reception from their destination. A primary cause for the "funeral effect" is that the same packets are alternate routed at a number of nodes in the system. Consequently, the individual packets which have been alternate routed never reach the destination assigned to them. Additionally, the alternate routed packets affect the delay of packets being scheduled for transmission on primary assigned routes. This, in turn, results in more packets being scheduled for transmission on their assigned alternate route, which further contributes to decreased "good" throughput in the system.